At present mobile traffic demands are increasing and will most likely exceed network capacities within the foreseeable future. One manner in which operators are fighting the increasing traffic demands is by utilizing heterogeneous access networks. In heterogeneous access networks, mobile operators can move traffic from the cellular network, where the capacity constraints are most severe, to cheaper shorter-range wireless local area networks e.g. Wi-Fi. One problem with such complex mixes of cellular networks and wireless local area networks is the implementation of efficient policies to control the mobility behavior of the user equipment when moving between the cellular network and the wireless local area network and also efficient radio access selection and traffic steering for the user equipment. In particular, there is little consistency between mechanisms used by e.g. Wi-Fi operators and those used by cellular operators to control for example network discovery, network selection, traffic prioritization, user authentication, roaming capabilities and quality of service (QoS). At present, this also applies for the case when it is the same cellular operator providing the Wi-Fi related information. Roaming capabilities may refer to the capabilities of the user equipment moving both between the cellular network and the wireless local area network and between cellular networks from different cellular operators.
In legacy 3GPP networks, the focus has been on network control of both user equipment (UEs) and usage of spectrum and network resources. There have been many arguments for that, e.g. the network has more information and thus ability to jointly optimize the network and end user performance, leading to user satisfaction at a lower cost. In addition, the performance becomes more predictable, because it does not depend on different UE implementations.
The information needed for efficient selection of the most suitable radio access technology (RAT) is large, is stored partly in the Core Network, and partly in the Radio. Network, see below FIG. 1. Almost all Core network information is currently passed on to the radio access network (RAN), mainly when the UE becomes “RRC Connected” and when “Radio Bearers” are added. Examples are cooperating/allowed PLMNs, subscription (allowed RATs, QoS rules), services (QoS rules). This information is passed for example over the respective so-called A/Gb, Iu and S1 interfaces. The RAN has information about e.g.: available cells and radio technologies, quality of existing and potential radio links, cell loads including the mix of UEs with different QoS requirements present in different cells, etc. RAN makes a composite decision, taking both Core Network and Radio Network information into account.
In contrast, the current WLAN-3GPP integration method is UE-centric. The UE is provided with (mainly) Core Network information using the ANDSF method; see below description in relation to FIG. 2. The content of this information is largely corresponding to the information that is passed over the so-called A/Gb, Iu and S1 interfaces. Furthermore, the existing interfaces between Core Network and 3GPP RAN has no WLAN-related information at all. Upgrading the Core Network to provide such WLAN-related information may be considered complex, since it affects many nodes.
The so-called Access Network Discovery and Selection Function (ANDSF) is a 3GPP defined function (since 3GPP Rel-8 and continues to evolve) and provides the possibility to send different policies to the UE for network discovery and selection (see FIG. 2). The communication between the UE and the ANDSF server is defined as an IP-based S14-interface. The communication between the UE and the ANDSF server typically consists of the following distinct information elements, access discovery information, inter-system mobility policies, and inter-system routing policies.                Access Discovery Information (ANDI) is used to provide access discovery information to the UE, which can assist the UE to discover available (3GPP and) non-3GPP access networks without the burden of continuous background scanning.        Inter-System Mobility Policies (ISMP) are policies which guide the UE to select the most preferable 3GPP or non-3GPP access. The ISMP are used for UEs that access a single access (3GPP or Wi-Fi) at a time.        Inter-System Routing Policies (ISRP) are policies which guide the UE to select over which access a certain type of traffic or a certain APN shall be routed. The ISRP are used for UEs that access both 3GPP and Wi-Fi simultaneously.The above ANDI, ISMP and ISRP have been extended with additional policies in the later 3GPP releases, for example WLAN selection policy (WLANSP) and Inter-APN Routing Policies (IARP) policies.        
The roaming architecture for ANDSF (source is FIG. 4.8.1.1-2 in 3GPP TS 23.402) is illustrated in FIG. 3 of this disclosure. As mentioned previously, the term roaming is used to indicate the mobility behavior when a user equipment moves between a cellular network and a wireless local area network or when a user equipment moves between cellular networks from different cellular operators.
The mobile network architecture for the case of LTE/EPC and Wi-Fi is illustrated in FIG. 4, with a multitude of interfaces represented between the various elements of the network.
At present focus has shifted to enable a less UE centric control of the use of 3GPP and WLAN. Consequently, there is a need to improve the architecture in order to allow a less UE centric control in heterogeneous wireless communication systems.